1. Field of the Invention
The present invention relates to an apparatus for analyzing the carbon content of metals, in which the metal sample to be analyzed is burned in a current of oxygen in a combustion furnace or a resistance furnace; the concentration of carbon dioxide and the like, contained in the gas generated in the furnace, is determined by means of a non-dispersive infrared analyzer; the carbon content of said metal sample is then calculated by an integration technique.
2. Description of the Prior Art
When a metallic sample is burned, all of the carbon contained therein is converted to carbon dioxide (CO.sub.2) or carbon monoxide (CO). Accordingly, the carbon content of the metallic sample may be determined by measuring the CO.sub.2 and CO concentrations. U.S. Pat. Nos. 3,305,318 and 3,985,505, respectively issued to E. L. Bennett and R. L. Bredeweg teach systems for determining the carbon content of a metallic sample from the measurement of the CO and CO.sub.2 concentrations. The disclosure contained in these two patents are incorporated by reference herein.
In the case of prior art analyzers, as a rule, not only carbon dioxide, but also carbon monoxide is generated at a ratio of several percent therebetween, based on the content of carbon dioxide when the metal sample is burned. Accordingly, in the conventional apparatus as shown in FIG. 1, gas generated in a combustion furnace 3' is passed through an oxidizer 7' to convert carbon monoxide to carbon dioxide and then the concentration of carbon dioxide is determined by means of a non-dispersive infrared analyzer 9' of carbon dioxide or, as shown in FIG. 2, the concentration of carbon dioxide and carbon monoxide generated in a combustion furnace 3' is respectively determined by means of a non-dispersive infrared analyzer 9'a of carbon dioxide and a non-dispersive infrared analyzer 9'b of carbon monoxide; the measurement values of analyzers 9a and 9b are then added electrically by means of an adder 10'. Referring now to FIG. 1 and FIG. 2, 1' designates an oxygen cylinder, 2' designating a refiner, 4' designating a dust filter, 5' designating a desiccating agent and 6' designating a flow rate regulator.
However, in the former prior art system (FIG. 1), the use of said oxidizer 7' leads to the oxidation of SO.sub.2, contained in the gas generated in said combustion furnace 3', to SO.sub.3 which interferes with the determination of carbon dioxide. Consequently it is necessary to use an SO.sub.3 -removing agent 8'.
In the latter prior art system (FIG. 2), two pairs of infrared analyzer 9'a and 9'b, and adder 10' are required, resulting in a plurality of expensive elements. Accordingly, the apparatus cost and the resulting analyzing costs become high.